The NYCLU is a public-interest law firm that principally addresses issues involving challenges to a government law, policy or practice affecting the constitutional rights – that is, the civil liberties and civil rights – of a significant number of people arising in New York State. Find out how to get help with such an issue.

He must - how else do you explain the blank check to blanket New York with enough surveillance cameras to track millions of us going to work, taking our kids to school or stopping into a corner store?

This month, he vowed to "spend as much as necessary" to install a web of high-tech surveillance cameras documenting every move New Yorkers make on every street and sidewalk in midtown Manhattan between 30th and 60th Sts. Clearly he can't control himself.

At least $24 million in federal homeland security grants would be spent on the project, an expansion of the $100 million "Ring of Steel" surveillance network already being developed in lower Manhattan below Canal St. That's $124 million to monitor and track millions of law-abiding citizens with thousands of digital cameras and license plate scanners.

That $124 million will get us a surveillance web so intrusive that it categorizes as "suspicious behavior" simply driving around the block three times. Does that mean that anyone who tries to find parking on the street will be treated as a potential terrorist?

What's more, the system will allow the NYPD to create a computerized database on the movement and whereabouts of millions of people whose only "crime" is walking down a public street.

A plan of this scope, expense and intrusiveness demands robust public debate and legislative oversight. The City Council must establish a formal public review process for this costly proposal and make sure our privacy is protected. Unfortunately, none of this is happening. There have been no City Council meetings devoted to this issue. We know next to nothing about this massive expansion of the NYPD's surveillance power.

In fact, the NYPD has shrouded the project in secrecy, refusing to disclose even basic details of the project. We don't know what information is being collected, who has access to it and how long it is being stored.

The New York Civil Liberties Union has sued the NYPD and the federal government for this information, and those lawsuits are pending. But we shouldn't have to file lawsuits to have an informed discussion about a proposal that affects the privacy rights of millions.

The mayor claims that surveillance cameras can stop terrorists. Sadly, history suggests otherwise. London's "Ring of Steel" surveillance system, the model for the New York system, failed to prevent the July 7, 2005, transit bombings that killed 56 people and wounded more than 700.

While surveillance cameras played an important role in solving that horrific crime, their ability to deter terrorists has never been proven and our City Council has never considered whether our money would be better spent on putting more cops on the street or strengthening security at our ports.

What we do know is that these cameras jeopardize the privacy of every New Yorker. Yet the Police Department has refused to adopt meaningful safeguards to ensure that videos and photos do not fall into the wrong hands.

Mayor Bloomberg's unhealthy obsession with cameras shouldn't trump the informed, vigorous debate New Yorkers deserve. The city should put its expanded surveillance plans on hold until that happens.

Lieberman is executive director of the New York Civil Liberties Union.